Abstract
Purpose: :
Voltage-gated calcium channels are transmembrane proteins that mediate numerous neuronal functions such as the rapid influx of Ca2+, transmitter release, gene transcription and synaptic plasticity. They are heteromultimeric channels consisting of an α1 subunit, and auxiliary α2Δ1- α2Δ4, and β subunits. Whereas some studies reported the presence of α2Δ1-3 in the brain, the expression and localization of the α2Δ4 accessory subunit in the rodent brain and retina remain unclear.
Methods: :
To determine the expression of the α2Δ4 gene, we used RT-PCR from different tissues of mouse and rat with specific primers. The cellular localization of the α2Δ4 subunit was studied by single and double immunostaining in rodent retinal slices using well characterized antibodies.
Results: :
We found α2Δ4 mRNA in brain, retina, lung, liver, optic nerve and heart of mouse and rat. In the retina, we found α2Δ4 subunit to be strongly localized in Mueller cells, including Mueller cell endfeet, putative displaced ganglion cells and in the outer plexiform layer, brightly fluorescent puncta consistent with their expression in rod bipolar cells and photoreceptor terminals.
Conclusions: :
This is the first study that shows the localization of the α2Δ4 subunit in the mouse and rat retina.In conclusion, α2Δ4 subunit may play regulatory roles in the ribbon synapses between photoreceptors and bipolar cells by modifying the properties of the channel.
Keywords: calcium • synapse • immunohistochemistry